I have been trying to fix the problem of this code but unfortunately It keep saying ERORR on line 71 which is [y= dfl(xo)\fl(xo)]. Need to help?

function[final_comp]=eq_model_const(g_temp,ele_comp,m)

format short

tol=0.00001;

maxit=100;

%disp('elemental composition should be of the form [C, H, O, N, Ash]');

%ele_comp=input('Enter elemental composition of biomass: ');

%disp('Initial guess is of the form [H2 CO CO2 H2O CH4] ')

xx0=[0.1,0.1,0.1,0.1,0.1]';

% Heat of formation of different compounds at 25 C, kJ/kmol

H_f_H2O_g=-241818;H_f_H2O_l=-285830;H_f_CO2=-393509;H_f_CO=-110525;

H_f_CH4=-74520;H_f_H2=0;H_f_O2=0;H_f_N2=0;

%Function for finding sensible heat for various gases constants

C_p_H2O=[32.24 0.1923e-2 1.055e-5 -3.595e-9];

C_p_H2=[29.11 -0.1916e-2 0.4003e-5 -0.8704e-9];

C_p_CO=[28.16 0.1675e-2 0.5372e-5 -2.222e-9];

C_p_CO2=[22.26 5.981e-2 -3.501e-5 -7.469e-9];

C_p_CH4=[19.89 5.204e-2 1.269e-5 -11.01e-9];

C_p_N2=[28.90 -0.1571e-2 0.8081e-5 -2.873e-9];

%finding general equations for calculating k1 and k2

G_CO=[3.376 0.557e-3 0 -0.031e5 -110525 -137169];

G_CO2=[5.457 1.045e-3 0 -1.157e5 -393509 -394359];

G_H2O=[3.470 1.450e-3 0 0.121e5 -241818 -228572];

G_H2=[3.249 0.422e-3 0 0.083e5 0 0];

G_C=[1.771 0.771e-3 0 -0.867e5 0 0];

G_CH4=[1.702 9.081e-3 -2.164e-6 0 -74520 -50460];

delta_ws_final=[];

delta_meth_final=[];

for iii=1:6

delta_ws=G_H2(iii)+G_CO2(iii)-G_CO(iii)-G_H2O(iii);

delta_meth=G_CH4(iii)-G_C(iii)-2*G_H2(iii);

delta_ws_final=[delta_ws_final delta_ws];

delta_meth_final=[delta_meth_final delta_meth];

end

T_0=298.15;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

k1= 9.72e-02;

k2= 1.14561;

%%%%%%%%function for calculating int_eq_sp

function int_for_gibbs_difff1= int_eq_sp1(difff,g_temp)

tau=g_temp/298.15;

int_for_gibbs_difff1=difff(1).*log(tau)+((difff(2).*T_0+((difff(3)*T_0^2+(difff(4)/(tau^2.*T_0^2)))*((tau+1)/2)))*(tau-1));

end

%%%%%%%%%%%%%%%%%%%%

function int_for_gibbs_difff2= int_eq_sp2(var_sp,g_temp)

tau=g_temp/298.15;

int_for_gibbs_difff2=var_sp(1).*T_0*(tau-1)+var_sp(2)*0.5*T_0^2*(tau^2-1)+var_sp(3)*T_0^3*(tau^3-1)/3+var_sp(4)*(tau-1)/(tau*T_0);

end

%k1=9.72e-02;k2=1.4561;

%%%%finding lambda and gamma for below calculations%%%%%%%%%%%%%%%%%%%%%%%%%

norm_1_C = 20/(12);

norm_1_H = 25/(1.008);

norm_1_O = 35/(16);

norm_1_N= 25 /(14.007);

lambda = norm_1_H/norm_1_C ;

gamma = norm_1_O/norm_1_C ;

beta = norm_1_N/norm_1_C ;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

x0=xx0;

iter=1;

iter_m=1;

sol_final=[];

w=0;

Moisture_Content=[];

for N=1:length(w)

Moisture_Content=[Moisture_Content 18*100*w(N)/(24+18*w(N))];

end

Moisture_Content;

%%%%%%%%%%%%%%%%%Main Loop for solving the equations of interests

for iter_m=1:length(w)

while(iter<=maxit)

y =-dfl(x0)\f1(x0);

xn=x0+y;

err=max(abs(xn-x0));

if(err<=tol)

x=xn;

else

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

x0=xn;

end

iter=iter+1;

end

iter=1;

sol_temp=x;

sol_final=[sol_final sol_temp];

iter_m=iter_m+1;

end

%Multiplying m with 3.76 to get correct N2 moles

p=length(w);

frac_N2=[];

for l=1:p

frac_N2=[frac_N2 m*3.76];

end

final_comp=[sol_final(1:5,1:p);frac_N2];

%fin_rep=input('Do you want to find syngas composition in dry syngas basis(y/n): ','s');

fin_rep='n';

if fin_rep=='n';

%finding total amount of product gas for each moisture content

total_frac_m=[];

for n=1:p

total_frac_m=[total_frac_m sum(final_comp(1:6,n))];

end

total_frac_m; %sum of all product gases

else

%finding total amount of product gas on dry basis for each moisture content

dry_final_comp=final_comp;

dry_final_comp(4,:)=[];

total_frac_m=[];

for n=1:p

total_frac_m=[total_frac_m sum(dry_final_comp(1:5,n))];

end

total_frac_m;

final_comp=dry_final_comp;

end

%expressing all the components in molar fraction or volumetric fraction

final_frac_comp=[];

for MM=1:length(total_frac_m)

final_frac_m=[];

if fin_rep=='y'

l_in=length(xx0);

else

l_in=length(xx0)+1;

end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

for NN=1:l_in

inal_frac_m=[final_frac_m;final_comp(NN,MM)/total_frac_m(MM)];

end

final_frac_comp=[final_frac_comp final_frac_m];

end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function f=f1(X)

x_1=X(1); x_2=X(2); x_3=X(3);x_4=X(4);x_5=X(5);

val_1=x_2+x_3+x_5-1;

val_2=x_1+x_4+2*x_5-w(iter_m)-(lambda/2);

val_3=x_2+2*x_3+x_4-2*m-gamma-w(iter_m);

val_4=-k1*x_1^2+(x_5*(x_1+x_2+x_3+x_4+x_5+3.76*m));

val_5=x_2*x_4*k2-x_1*x_3;

f=[val_1; val_2;val_3;val_4;val_5];

end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function df=df1(X)

x_1=X(1); x_2=X(2); x_3=X(3);x_4=X(4);x_5=X(5);

df=[0,1,1,0,1;1 0 0 1 2; 0 1 2 1 0;-2*x_1*k1+x_5,x_5,x_5,x_5,2*x_5+(x_1+x_2+x_3+x_4+3.76*m); -x_3 k2*x_4-x_1 k2*x_2 0];

end

end

THIS WAS THE ERORR DISPLAYED

Unrecognized function or variable 'dfl'.

Error in eq_model_const (line 71)

y =-dfl(x0)\f1(x0);

[John D'Errico]

What is the error? You do not tell us what the COMPLETE error is, so someone would need to ty to run the code. But you do not provide sufficient information to know even how you ran the code. That makes it impossible to help you.

When you ask about an error, REPORT THE COMPLETE ERROR. EVERYTHING IN RED.

Show how you called the function, and with what inputs, since this is a function.

Better yet would be to learn to use the debugger, in which case you might be able to solve the problem yourself. But at least make it possible for someone to help you.

[Aspetos Truth]

Okay I will do my best. Thank you for the feedback.

Answer 1

[Jan]

"Unrecognized function or variable 'dfl'." - The error message seems to be clear: The expression "dfl" is unknown. Do you expect it to be an array or a function? Where is it defined?

Your code contains a function called "df1" - D-F-One, while the failing line contains "dfl" - D-F-lowercase L. Maybe this is a typo only?

Use a font, in which l (lowercase L) and 1 (one) and I (uppercase i) looks different. The same problem concerns O (uppercase oh) and 0 (zero).

[Aspetos Truth]

Thank you so much I appreciate the what you are doing. I couldn't agree more. I will accept your answer it was a typing mistake due to the font resemblance. But still the error shows up like this.

Not enough input arguments.

Error in eq_model_const/df1 (line 142)

df=[0,1,1,0,1;1 0 0 1 2; 0 1 2 1 0;-2*x_1*k1+x_5,x_5,x_5,x_5,2*x_5+(x_1+x_2+x_3+x_4+3.76*m);

-x_3 k2*x_4-x_1 k2*x_2 0];

Error in eq_model_const (line 71)

y =-df1(x0)\f1(x0);

WHAT SHOULD I DO?

[Jan]

@Aspetos Truth: Please remember that UPPERCASE means shouting. Calm down.

Use the debugger to find the cause of such problems. Type in the command window:

dbstop if error

Run the code again. If Matlab stops at the error, inspect the currently processed line.

    df = [0,1,1,0,1; ...
          1 0 0 1 2; ...
          0 1 2 1 0; ...
          -2*x_1*k1+x_5, x_5, x_5, x_5, 2*x_5+(x_1+x_2+x_3+x_4+3.76*m); ...
          -x_3 k2*x_4-x_1 k2*x_2 0];    

Process the 2 last lines in the command window. Which of them is failing? Process this line in parts. to find the problem.

My guess(!) is, that m is undefined, because you have called the function

    eq_model_const(g_temp,ele_comp,m)    

with too few input arguments.

[Aspetos Truth]

Jan , how are you? I have tried to fix the codes problem as you have suggested, and thanks to you I it has worked, but still I need your guidance on some part of the coding. The corrected code looks like this.

function[final_comp]=eq_model_const(g_temp,ele_comp,m)
format short
tol=0.00001;
maxit=100;
%disp('elemental composition should be of the form [C, H, O, N, Ash]');
ele_comp=input('Enter elemental composition of biomass: ');
%disp('Initial guess is of the form [H2 CO CO2 H2O CH4] ')
g_temp = input('Please enter the gasification temperature Tg =');
m = input('Please enter the equivalence ratio=');
xx0=[0.1,0.1,0.1,0.1,0.1]';
% Heat of formation of different compounds at 25 C, kJ/kmol
H_f_H2O_g=-241818;H_f_H2O_l=-285830;H_f_CO2=-393509;H_f_CO=-110525;
H_f_CH4=-74520;H_f_H2=0;H_f_O2=0;H_f_N2=0;
%Function for finding sensible heat for various gases constants
C_p_H2O=[32.24 0.1923e-2 1.055e-5 -3.595e-9];
C_p_H2=[29.11 -0.1916e-2 0.4003e-5 -0.8704e-9];
C_p_CO=[28.16 0.1675e-2 0.5372e-5 -2.222e-9];
C_p_CO2=[22.26 5.981e-2 -3.501e-5 -7.469e-9];
C_p_CH4=[19.89 5.204e-2 1.269e-5 -11.01e-9];
C_p_N2=[28.90 -0.1571e-2 0.8081e-5 -2.873e-9];
%finding general equations for calculating k1 and k2
G_CO=[3.376 0.557e-3 0 -0.031e5 -110525 -137169];
G_CO2=[5.457 1.045e-3 0 -1.157e5 -393509 -394359];
G_H2O=[3.470 1.450e-3 0 0.121e5 -241818 -228572];
G_H2=[3.249 0.422e-3 0 0.083e5 0 0];
G_C=[1.771 0.771e-3 0 -0.867e5 0 0];
G_CH4=[1.702 9.081e-3 -2.164e-6 0 -74520 -50460];
delta_ws_final=[];
delta_meth_final=[];
for iii=1:6
    delta_ws=G_H2(iii)+G_CO2(iii)-G_CO(iii)-G_H2O(iii);
    delta_meth=G_CH4(iii)-G_C(iii)-2*G_H2(iii);
    delta_ws_final=[delta_ws_final delta_ws];
    delta_meth_final=[delta_meth_final delta_meth];
end
T_0=298.15;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
k1= 9.72e-02;
k2= 1.14561;
%%%%%%%%function for calculating int_eq_sp
    function int_for_gibbs_difff1= int_eq_sp1(difff,g_temp)
        tau=g_temp/298.15;
        int_for_gibbs_difff1=difff(1).*log(tau)+((difff(2).*T_0+((difff(3)*T_0^2+(difff(4)/(tau^2.*T_0^2)))*((tau+1)/2)))*(tau-1));
    end
%%%%%%%%%%%%%%%%%%%%
    function int_for_gibbs_difff2= int_eq_sp2(var_sp,g_temp)
        tau=g_temp/298.15;
        int_for_gibbs_difff2=var_sp(1).*T_0*(tau-1)+var_sp(2)*0.5*T_0^2*(tau^2-1)+var_sp(3)*T_0^3*(tau^3-1)/3+var_sp(4)*(tau-1)/(tau*T_0);
    end
%k1=9.72e-02;k2=1.4561;
%%%%finding lambda and gamma for below calculations%%%%%%%%%%%%%%%%%%%%%%%%%
norm_1_C = 	ele_comp(1)/(12);
norm_1_H = ele_comp(2)/(1.008);
norm_1_O = ele_comp(3)/(16);
norm_1_N= ele_comp(4)/(14.007);
lambda = norm_1_H/norm_1_C ;
gamma = norm_1_O/norm_1_C ;
beta = norm_1_N/norm_1_C ;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
x0=xx0;
iter=1;
iter_m=1;
sol_final=[];
w=0;
Moisture_Content=[];
for N=1:length(w)
    Moisture_Content=[Moisture_Content 18*100*w(N)/(24+18*w(N))];
end
Moisture_Content;
%%%%%%%%%%%%%%%%%Main Loop for solving the equations of interests
for iter_m=1:length(w)
    while(iter<=maxit)
        y =-df1(x0)\f1(x0);
        xn=x0+y;
        err=max(abs(xn-x0));
        if(err<=tol)
            x=xn;
        else
            %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
            x0=xn;
        end
        iter=iter+1;
    end
    iter=1;
    sol_temp=x;
    sol_final=[sol_final sol_temp];
    iter_m=iter_m+1;
end
%Multiplying m with 3.76 to get correct N2 moles
p=length(w);
frac_N2=[];
for l=1:p
    frac_N2=[frac_N2 m*3.76];
end
final_comp=[sol_final(1:5,1:p);frac_N2];
%fin_rep=input('Do you want to find syngas composition in dry syngas basis(y/n): ','s');
fin_rep='n';
if fin_rep=='n';
    %finding total amount of product gas for each moisture content
    total_frac_m=[];
    for n=1:p
        total_frac_m=[total_frac_m sum(final_comp(1:6,n))];
    end
    total_frac_m; %sum of all product gases
else
    %finding total amount of product gas on dry basis for each moisture content
    dry_final_comp=final_comp;
    dry_final_comp(4,:)=[];
    total_frac_m=[];
    for n=1:p
        total_frac_m=[total_frac_m sum(dry_final_comp(1:5,n))];
    end
    total_frac_m;
    final_comp=dry_final_comp;
end
%expressing all the components in molar fraction or volumetric fraction
final_frac_comp=[];
for MM=1:length(total_frac_m)
    final_frac_m=[];
    if fin_rep=='y'
        l_in=length(xx0);
    else
        l_in=length(xx0)+1;
    end
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    for NN=1:l_in
        inal_frac_m=[final_frac_m;final_comp(NN,MM)/total_frac_m(MM)];
    end
    final_frac_comp=[final_frac_comp final_frac_m];
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    function f=f1(X)
        x_1=X(1); x_2=X(2); x_3=X(3);x_4=X(4);x_5=X(5);
        val_1=x_2+x_3+x_5-1;
        val_2=x_1+x_4+2*x_5-w(iter_m)-(lambda/2);
        val_3=x_2+2*x_3+x_4-2*m-gamma-w(iter_m);
        val_4=-k1*x_1^2+(x_5*(x_1+x_2+x_3+x_4+x_5+3.76*m));
        val_5=x_2*x_4*k2-x_1*x_3;
        f=[val_1; val_2;val_3;val_4;val_5];
    end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    function df=df1(X)
        x_1=X(1); x_2=X(2); x_3=X(3);x_4=X(4);x_5=X(5);
        df=[0,1,1,0,1;1 0 0 1 2; 0 1 2 1 0;-2*x_1*k1+x_5,x_5,x_5,x_5,2*x_5+(x_1+x_2+x_3+x_4+3.76*m); -x_3 k2*x_4-x_1 k2*x_2 0];
    end
end

And after running it and entering the input values the error window pops up

eq_model_const

Enter elemental composition of biomass: [ 48.31, 6.28, 44.15, 0.53, 0.73]

Please enter the gasification temperature Tg =600

Please enter the equivalence ratio=0.3

Index exceeds the number of array elements (0).

Error in eq_model_const (line 52)

norm_1_C = ele_comp(1)/(12);

ans =

48.3100 6.2800 44.1500 0.5300 0.7300

• And trying with another method

eq_model_const

Enter elemental composition of biomass: {48.31,6.28,44.15,0.53,0.73}

Please enter the gasification temperature Tg =600

Please enter the equivalence ratio=0.3

Index exceeds the number of array elements (0).

Error in eq_model_const (line 52)

norm_1_C = ele_comp(1)/(12);

ans =

1×5 cell array

{[48.3100]} {[6.2800]} {[44.1500]} {[0.5300]} {[0.7300]}

So, Jan what should I do?

[Jan]

@Aspetos Truth: Please use the tools to format code. This improves the readability.

ans =
48.3100    6.2800   44.1500    0.5300    0.7300

This is the answer to what?

You define the function with input arguments:

function[final_comp]=eq_model_const(g_temp,ele_comp,m)

But then the inputs are overwritten by input() commands. Prefer to call the function with input arguments instead:

eq_model_const(600, [48.31, 6.28, 44.15, 0.53, 0.73], 0.3)

and omit the input() lines. Then the calls are reproducible.